12P Pons-Brooks

Closest to Sun on 2024 April 21 at 0.78AU.
Closest to Earth on 2024 June 2 at 1.54AU.
Maximum magnitude 4.0 in April 2024
Orbital period 71 years (Halley type)


12P Pons-Brooks. 2024 May 5 at 09:00UT.
using a C11 RASA f/2.2 + Canon 6D. iso3200 20x30sec. FOV 3 deg. North up. near Swan Hill, Victoria, Aus

 

In 1986, after the appearance of comet 1P Halley, I asked the question, what is the next best once in a lifetime periodic comet?
The answer was 12P Pons-Brooks, but I had to wait another 38 years for it. That time has finally arrived.
Pons-Brooks has an orbital period of 71 years, and is referred to as a "Halley” type comet.
Jean-Louis Pons, the greatest visual comet discoverer of all time with a tally of 37 comets, discovered 12P in 1812.
It was rediscovered in 1883 by William R Brooks, the 2nd most prolific comet discoverer with a tally of 27 comets.
12p was the 12th periodic comet recognised in historical records, hence its designation.
The comet last returned in 1954 but the return was not very favourable, however it was noted for its large pre-perihelion outbursts.
A recent paper publication by Maik Meyer has identified 12P at previous historical apparitions in 1457 and 1385CE.
2024 is now the 6th recorded appearance.

The 2024 passage

The comet is at perihelion, its closest point to the Sun, on 2024 April 21 at a distance of 0.78 astronomical units (AU)
which corresponds to 117 million kilometres. Later it has a relatively distant Earth approach of 1.54 AU on June 2.

Why is 12P Pons-Brooks not as famous as 1P Halley?
Its perihelion distance is larger (0.78AU vs 0.58AU).
It has a steep orbital inclination (74 degrees) which means that the comet doesn't spend a lot of time near the ecliptic, where the Earth and other planets lie.
Comet Halley travels in a direction opposite that of the planets and usually has a close but brief encounter with the Earth at each return.
12P has one big advantage over 1P Halley. Its size is at least double (30km vs 15km).
12P would have been situated much closer to the Earth had it arrived during the month of December. An April arrival is not very favourable.
Despite this setback, southern hemisphere observers will still see the comet low in the evening sky commencing in late April 2024
when the comet is expected to shine at its brightest, 4th magnitude.
During the early part of 2024, 12P Pons-Brooks was mainly a northern hemisphere object due to its high orbital inclination,
but southern hemisphere observers are favoured for the post-perihelion spectacle, as the comet heads southwards.
I mentioned 12P had a history of repeat outbursts.
Sticking to form, the first reported outburst at the 2024 return was detected back in 2023 July 20
when the comet brightened +5 orders of magnitude. Initially stellar in appearance at magnitude 11.6,
the outburst expanded and diffused out over the weeks following, as it returned to pre-outburst levels of magnitude 16.
Its heliocentric distance at the time was 3.9AU, well beyond the zone of water ice sublimation. So what was causing this activity?
This type of behaviour is very similar to the well-studied annual comet 29P Schwassmann-Wachmann a
nd is likely due to cryovolcanic eruptions on a large, slowly rotating nucleus, involving volatile ice such as carbon monoxide, carbon dioxide and methane.

The British Astronomical Association Comet Section are running a programme to measure the brightness of this comet in a small aperture near to the nucleus.
This shows the outbursts more clearly than measuring the total magnitude of the comet. Please visit

https://britastro.org/section_news_item/12p-pons-brooks-observing-campaign

A paper published at the Astronomers Telegram on “the rotation period of comet 12P/Pons-Brooks from CN coma morphology”
indicated a period of approximately 57 hours.

My photos and observations appear in chronological order, below the observing guide.

Comet 12P Pons-Brooks observing guide
This comet is notable for its regular outbursts. Magnitudes quoted below are a baseline value.
The comet could appear significantly brighter at any time. Outburst typically last several days,
followed by a return to baseline brightness. Outbursts offer a tremendous level of detail in the nucleus,
with spiral jets and horns potentially visible at any time. The activity in the ion tail usually increases dramatically.


April 2024
the comet is initially observable from northern hemisphere skies but starts its journey southwards,
finally becoming visible to southern hemisphere observers by the end of the month.
It is best observed LOW in the evening sky after dusk, trekking south-eastwards through the constellations of Aries
and Taurus, brightening from magnitude 5 to 4.5.
The best period of visibility is between April 1 to 10 (northern hemisphere), and then from April 27 (southern hemisphere).
On April 12, it will be 3 degrees west of Jupiter.
The comet reaches minimum solar elongation of 22 degrees on April 22 and will be a difficult object low in twilight.
Northerners lose sight of the comet.

Southerners had their first views around April 20, about an hour after sunset.
You will need a clear western horizon, preferably situated at a rural location.
Best period of visibility occurs between April 27 to May 13

with the comet at its brightest and moonlight does not interfere with the view,
offering possible naked eye views from a dark site, but atmospheric extinction will make it less likely.


May 2024

Night mode charts are set for 35S latitude (covering most of Australian capital cities)
the comet remains restricted to southern hemisphere observers.
It is best observed in the evening sky after dusk, trekking south-eastwards through the constellations of
Taurus, Eridanus and Lepus, fading from magnitude 5 to 6.
The best period of visibility is between May 1 to 12, and then from May 26.
On May 10, it will be 1 degree west of Nu Eridanii.
On May 24, it will be adjacent to Lambda Lepii.
On May 29, it will be 1.3 degrees east of Arneb (Alpha Lepii)

June 2024

Night mode charts are set for 35S latitude (covering most of Australian capital cities)
the comet remains restricted to southern hemisphere observers.
It is best observed in the evening sky after dusk, trekking south-eastwards through the constellations of
Lepus, Canis Major and Puppis, fading from magnitude 6.0 to 7.5.
The best period of visibility is between June 1 to 10, and then from June 24.
On June 3, it will be 1.3 degrees east of Delta Lepii.
On June 15, it will be adjacent to magnitude 11 spiral galaxy NGC 2280 in Canis Major.
On June 18, it will be 30’ southwest of Epsilon Canis Majoris (Adhara)

July 2024

Night mode charts are set for 35S latitude (covering most of Australian capital cities)
the comet remains restricted to southern hemisphere observers.
It is best observed in the evening sky after dusk, trekking eastwards through the constellations of
Puppis and Vela, fading from magnitude 7.5 to 9.0.
The best period of visibility is between July 1 to 9, and then from July 23.
On July 9-10, it will be a degree north of diffuse nebula NGC 2626 in Vela.
On July 31, it will be 1.3 degrees north of magnitude 6 globular cluster NGC 3201.

August 2024

Night mode charts are set for 35S latitude (covering most of Australian capital cities)
the comet remains restricted to southern hemisphere observers.
It is best observed in the evening sky after dusk, trekking eastwards through the constellations of
Vela and Centaurus, fading from magnitude 9.0 to 10.5.
The best period of visibility is between August 1 to 8, and then from August 21.
On August 2, it will be 1.5 degrees south of the galaxy group NGC 3256_61_63.

September 2024

Night mode charts are set for 35S latitude (covering most of Australian capital cities)
the comet remains restricted to southern hemisphere observers.
It is best observed in the evening sky after dusk, trekking eastwards through the constellation of
Centaurus, fading from magnitude 10.5 to 12.
The best period of visibility is between September 1 to 6, and then from September 19.
On September 12, it will be 1.3 degrees south of galaxy pair NGC 4835_4835A.
On September 15-16, it will be 2 degrees north of magnitude 9 spiral NGC 4945.
On September 23, it will transit the great globular cluster Omega Centauri (NGC5139)
but will likely be drowned out by the bright core. Either side of this date will be more preferable.

This may well be the last time 12P is visually observable.
It will next return to perihelion on August 11, 2095.
Unfortunately this will be another unfavourable appearance for the next generation of observers.
 

Comet 12P Pons-Brooks Observations


Comet 12P Pons-Brooks.
Image taken on 2024 May 13 at 09:00UT using a C11 RASA f/2.2 + Canon 6D. iso3200 20x30sec. FOV 2 deg.
North up. from Swan Hill, Victoria, Australia.
magnitude estimate through 8x40mm binoculars = 5.2, dia 5' dc 6, tail 1.5 degrees in PA 130.
Lots of lovely streamers on the ion tail.


The run of clear nights continued. 12P Pons-Brooks on 2024 May 7 at 09:00UT.
using a C11 RASA f/2.2 + Canon 6D. iso3200 20x30sec. FOV 3 deg. North up. near Swan Hill, Victoria, Aus
naked eye estimate was 4.5, 8x40mm = 4.9, 2 degree tail in PA125
The ion tail appeared quite intense. Note the lovely ion streamer bending upwards from the nucleus.
Note the sunward facing dust fan. The dust tail will close in on itself during May.
Earth will cross the comets orbital plane on June 6, resulting in a dust "anti-tail"
 


12P Pons-Brooks on 2024 May 6 at 09:00UT. using a C11 RASA f/2.2 + Canon 6D. iso3200 20x30sec.
FOV 3 deg. North up. near Swan Hill, Victoria, Aus
I made my first naked eye observation this evening m1=4.5. Comet has finally moved out of twilight.
Using 8x40mm Binoculars m1= 4.9, tail 2 degrees long in PA 125

Telephoto lens of 12P Pons-Brooks, taken on 2024 May 6 at 09:00UT using a Canon 60Da + Sigma 200mm.
30x30sec iso1600. FOV 4 deg. North up. near Swan Hill, Victoria, Aus.
The ion tail is 4 degrees long in PA123 ending at DZ Eridanii. The dust tail is 2 degrees long in PA 30
Tracked using Skywatcher star adventurer mount. Calibrated and stacked using Deepskystacker.
Processed using Maxim DL6


12P Pons-Brooks. 2024 May 5 at 09:00UT. Canon 60Da + Sigma 200mm. 30x30sec iso1600.
FOV 4 deg. North up. Swan Hill, Victoria, Aus.
 


12P Pons-Brooks. 2024 May 1 at 09:00UT. Canon 60Da + Sigma 200mm. 30x30sec iso1600.
FOV 4 deg. North up. Swan Hill, Victoria, Aus.
 


Comet 12P Pons-Brooks on 2024 May 1 at 09:00UT.
using a C11 RASA f/2.2 + Canon 6D. iso1600 15x30sec. FOV 3 deg. North up. near Swan Hill, Victoria, Australia.
Stacked in Deepskystacker. Processed in Maxim DL.
The blue ion tail is less active tonight, but the tuffs of smoke are likely disconnections.
The yellow dust tail has sharp curvature towards the north. Visual estimate through 8x40mm binoculars = 4.9.
Visual tail about 1 degree. Not visible to the naked eye due to low altitude.
 


Comet 12P Pons-Brooks on 2024 April 30 at 09:00UT
using a C11 RASA f/2.2 + Canon 6D. ISO1600 10x30sec. FOV 3 deg. North up. near Swan Hill, Victoria, Australia.
The blue ion tail is incredibly active. The well separated yellow dust tail has sharp curvature towards the north.
Visual estimate through 8x40mm binoculars = 4.8
Visual tail about 1 degree. Not visible to the naked eye.


Image of 12P on 2024 April 30th. Note the smoky appearance of the ion tail due to numerous disconnections from the comet.


12P Pons-Brooks on 2024 April 29 at 09:00UT.
using a Canon 6D + Sigma 200mm. 20x20sec iso1600. FOV 4 deg. North lower right. from Swan Hill, Victoria, Aus.
Note the big bend in the ion tail, affected by the turbulent solar wind. The well separated dust tail has sharp curvature towards the north.
Visual estimate through 8x40mm binoculars = 4.5
Not visible to the naked eye.


12P Pons-Brooks on 2024 April 26 at 09:00UT combining 9 minutes of data


12P Pons-Brooks on 2024 April 26 at 09:00UT.
(7pmAEST) using a Canon 6D + Sigma 200mm f/2.8 lens. 15x20sec iso1600. FOV 5 deg. North lower right. near Swan Hill, Victoria, Australia.
Tracked using Skywatcher star adventurer mount.
Image was taken at moonrise but henceforth will not interfere for the following 2 weeks.
Total magnitude of the comet was estimated at 4.9 using 8x40mm binoculars.
Not visible to the naked eye due to low altitude and moonlight. Ion tail is 4 degrees long in this image.
Only half of this was visible in 15x70mm binoculars. Images calibrated and stacked using DeepSkyStacker.


12P Pons-Brooks taken on 2024 April 20 at 09:00UT
using a Canon 6D + Sigma 200mm. 3 mins. FOV 10 deg. North lower left. from Swan Hill, Victoria, Australia.
Although Pons-Brooks was brightest this weekend as it reached its closest point to the Sun, it was a difficult object low in evening twilight.
It is not visible to the naked eye, due to the effect of atmospheric extinction at such a low altitude.
estimate through 8x40mm binoculars = 4.5


Comet 12P Pons-Brooks in outburst on 2024 April 04 at 02:51UT.
Image taken remotely using I-TEL Utah T19 0.43-m f/6.8 reflector + CCD. 3 mins. FOV 30'. North up
Note the "jellyfish" appearance, similar to the super outburst of comet 17P Holmes in 2007
 

At its last return in 1954, it was notable for several, large pre-perihelion outbursts.
Sticking to form, the first reported outburst at the 2024 return was detected on 2023 July 20.82UT
My follow up observation a few hours later, on 2023 July 21 at 02:00UT indicated a +5 magnitude increase in brightness.
Initially stellar in appearance and magnitude 11.6, the outburst expanded and diffused out over the weeks following,
as it returned to pre-outburst levels (magnitude 16).
The comets heliocentric distance was 3.87AU, well beyond water ice sublimation.
This behaviour is very similar to the annual comet 29P Schwassmann-Wachmann and is likely due to
cryovolcanic activity on a large, slowly rotating nucleus involving highly volatile ices CO, CO2 and methane.
Another major eruption of +5 mag amplitude occurred on 2023 October 5 and on 2023 November 14.


12P Pons Brooks at outburst on 2023 November 19. Visual estimates at the time indicated comet was at 8th magnitude.


12P on 2023 September 05
 


12P Pons-Brooks on 2023 July 24 at 21:55UT.
Taken remotely using ITEL T18 Nerpio Spain 0.32-m f/5.3 CDK + QHY600. 10 mins. FOV 10'. UCAC4 V=12.0. North up.
+96hrs post outburst. The horns, 35" long in PA010.
Coma diameter = 60"


Animation of 12P over 4 days , 2023 July 21-24

12P Pons-Brooks on 2023 July 23 at 21:30UT.
Taken remotely using ITEL T18 Nerpio Spain 0.32-m f/5.3 CDK + QHY600. 10 mins. FOV 10'. UCAC4 V=12.0. North up.
+72hrs post outburst. The horns, 30" long in PA008.
Coma diameter = 50"

12P Pons-Brooks on 2023 July 22 at 21:30UT.
Taken remotely using ITEL T18 Nerpio Spain 0.32-m f/5.3 CDK + QHY600. 10 mins. FOV 10'. UCAC4 V=11.9. North up.
+48hrs post outburst. The horns, 20" long in PA008, are starting to become more pronounced as the coma expands.
coma diameter = 35"

12P Pons-Brooks on 2023 July 21 at 21:30UT. Taken remotely using ITEL T18 Nerpio Spain 0.32-m f/5.3 CDK + QHY600. 10 mins. FOV 5'. UCAC4 V mag =11.9. North up.
24hrs post outburst. Note the development of a horseshoe shape, with horns directed northwards.
Coma diameter = 25"

12P Pons-Brooks in outburst on 2023 July 21 at 02:00UT.
Taken remotely using I-TEL Nerpio Spain T18 0.32-m f/5.3 astrograph + CCD. 10 min stack on comet. FOV 20'. North up.
V mag =11.8 using UCAC4 reference stars
G mag = 11.6 using GAIA DR2 reference stars
Coma diameter = 17"

 

5 day ephemeris

P/Pons-Brooks (12P)
          Date RA            declination   r     delta  mag Elong Phase Con
---------------------------------------------------------------------------
 4 Dec 2023 12 18h32m38.64s +38 26' 28.3" 2.3468 2.5670 12.6 66.1 22.6 Lyr
 9 Dec 2023 12 18h42m37.18s +38 10' 28.8" 2.2847 2.5135 12.4 65.3 23.1 Lyr
14 Dec 2023 12 18h53m17.73s +37 58' 23.2" 2.2221 2.4587 12.2 64.6 23.6 Lyr
19 Dec 2023 12 19h04m42.25s +37 50' 08.6" 2.1591 2.4027 11.9 63.9 24.2 Lyr
24 Dec 2023 12 19h16m53.03s +37 45' 33.8" 2.0956 2.3459 11.7 63.2 24.8 Lyr
29 Dec 2023 12 19h29m53.02s +37 44' 20.3" 2.0317 2.2886 11.4 62.5 25.4 Cyg
 3 Jan 2024 12 19h43m45.69s +37 46' 05.1" 1.9673 2.2311 11.2 61.8 26.1 Cyg
 8 Jan 2024 12 19h58m34.70s +37 50' 18.0" 1.9025 2.1737 10.9 61.0 26.9 Cyg
13 Jan 2024 12 20h14m23.62s +37 56' 19.6" 1.8373 2.1168 10.6 60.1 27.7 Cyg
18 Jan 2024 12 20h31m15.73s +38 03' 15.3" 1.7717 2.0609 10.3 59.2 28.5 Cyg
23 Jan 2024 12 20h49m14.05s +38 09' 52.1" 1.7058 2.0063 10.0 58.1 29.3 Cyg
28 Jan 2024 12 21h08m21.22s +38 14' 41.1" 1.6396 1.9536 9.7 57.0 30.2 Cyg
 2 Feb 2024 12 21h28m38.75s +38 15' 59.4" 1.5733 1.9033 9.3 55.6 31.1 Cyg
 7 Feb 2024 12 21h50m06.23s +38 11' 49.8" 1.5068 1.8560 9.0 54.1 32.0 Cyg
12 Feb 2024 12 22h12m40.54s +38 00' 01.6" 1.4404 1.8119 8.7 52.4 32.9 Lac
17 Feb 2024 12 22h36m15.20s +37 38' 11.6" 1.3742 1.7717 8.3 50.5 33.7 Lac
22 Feb 2024 12 23h00m40.52s +37 03' 52.3" 1.3085 1.7357 7.9 48.4 34.4 And
27 Feb 2024 12 23h25m43.63s +36 14' 47.0" 1.2435 1.7043 7.6 46.1 35.0 And
 3 Mar 2024 12 23h51m08.85s +35 09' 01.3" 1.1796 1.6778 7.2 43.7 35.5 And
 8 Mar 2024 12 00h16m38.61s +33 45' 13.1" 1.1172 1.6561 6.8 41.0 35.7 And
13 Mar 2024 12 00h41m54.66s +32 02' 37.0" 1.0571 1.6393 6.4 38.3 35.6 And
18 Mar 2024 12 01h06m39.65s +30 01' 04.9" 0.9999 1.6270 6.1 35.5 35.3 Psc
23 Mar 2024 12 01h30m38.89s +27 41' 08.5" 0.9466 1.6187 5.7 32.6 34.6 Psc
28 Mar 2024 12 01h53m41.34s +25 03' 59.3" 0.8983 1.6137 5.3 29.9 33.6 Ari
 2 Apr 2024 12 02h15m40.02s +22 11' 22.2" 0.8565 1.6113 5.0 27.3 32.4 Ari
 7 Apr 2024 12 02h36m32.02s +19 05' 28.1" 0.8226 1.6102 4.8 25.2 31.2 Ari
12 Apr 2024 12 02h56m18.18s +15 48' 44.8" 0.7981 1.6094 4.6 23.5 30.1 Ari
17 Apr 2024 12 03h15m02.93s +12 23' 51.1" 0.7840 1.6077 4.4 22.7 29.6 Ari
22 Apr 2024 12 03h32m54.34s +08 53' 29.7" 0.7814 1.6046 4.4 22.8 29.9 Tau
27 Apr 2024 12 03h50m03.62s +05 20' 14.0" 0.7902 1.5994 4.5 23.8 30.9 Tau
 2 May 2024 12 04h06m44.18s +01 46' 11.9" 0.8100 1.5922 4.6 25.6 32.5 Tau
 7 May 2024 12 04h23m10.33s -01 47' 05.2" 0.8398 1.5834 4.9 28.1 34.4 Eri
12 May 2024 12 04h39m36.00s -05 18' 42.4" 0.8781 1.5737 5.1 31.0 36.3 Eri
17 May 2024 12 04h56m14.05s -08 48' 07.1" 0.9235 1.5641 5.5 34.2 38.0 Eri
22 May 2024 12 05h13m16.16s -12 14' 53.8" 0.9746 1.5555 5.8 37.6 39.4 Lep
27 May 2024 12 05h30m52.60s -15 38' 32.0" 1.0301 1.5493 6.1 41.1 40.3 Lep
 1 Jun 2024 12 05h49m11.96s -18 58' 18.0" 1.0890 1.5464 6.5 44.6 40.8 Lep
 6 Jun 2024 12 06h08m20.66s -22 13' 09.6" 1.1504 1.5481 6.9 48.0 41.0 Lep
11 Jun 2024 12 06h28m22.40s -25 21' 40.5" 1.2137 1.5552 7.2 51.3 40.7 CMa
16 Jun 2024 12 06h49m18.18s -28 21' 59.6" 1.2783 1.5685 7.6 54.3 40.2 CMa
21 Jun 2024 12 07h11m06.27s -31 12' 01.5" 1.3437 1.5889 7.9 57.1 39.4 CMa
26 Jun 2024 12 07h33m41.99s -33 49' 41.8" 1.4097 1.6168 8.3 59.7 38.5 Pup
 1 Jul 2024 12 07h56m57.60s -36 13' 14.5" 1.4760 1.6525 8.6 61.8 37.4 Pup
 6 Jul 2024 12 08h20m42.13s -38 21' 23.9" 1.5425 1.6960 9.0 63.6 36.2 Pup
11 Jul 2024 12 08h44m41.98s -40 13' 28.3" 1.6089 1.7472 9.3 65.1 35.0 Vel
16 Jul 2024 12 09h08m42.25s -41 49' 22.1" 1.6751 1.8059 9.6 66.1 33.7 Vel
21 Jul 2024 12 09h32m28.20s -43 09' 36.7" 1.7412 1.8715 10.0 66.7 32.4 Vel
26 Jul 2024 12 09h55m46.50s -44 15' 15.8" 1.8069 1.9436 10.3 67.0 31.2 Vel
31 Jul 2024 12 10h18m26.00s -45 07' 49.6" 1.8723 2.0216 10.6 66.9 29.9 Vel
 5 Aug 2024 12 10h40m17.94s -45 49' 02.3" 1.9373 2.1049 10.9 66.4 28.7 Vel
10 Aug 2024 12 11h01m16.16s -46 20' 39.0" 2.0018 2.1927 11.2 65.7 27.5 Vel
15 Aug 2024 12 11h21m17.18s -46 44' 18.8" 2.0660 2.2844 11.5 64.7 26.3 Cen
20 Aug 2024 12 11h40m19.92s -47 01' 31.8" 2.1296 2.3793 11.8 63.5 25.2 Cen
25 Aug 2024 12 11h58m25.38s -47 13' 38.5" 2.1929 2.4768 12.1 62.0 24.0 Cen